Social publishing is becoming a zero-sum game. As media companies clamor for readers on Facebook, Instagram and Snapchat, Twitter is losing the attention battle. Publishers are waking up to the fact that Twitter doesn’t have the audience scale, visual storytelling tools and ad products that the others do. For new media companies in particular, Twitter is a side job, said Paul Berry, CEO of RebelMouse. “It used to be one person on Facebook, one person on Twitter, and now it’s three people on Facebook and half a person on Twitter.”